electrodes and batteries

Abstract

To provide an electrode that satisfies both resistance reduction and improvement of cycle characteristics.SOLUTION: Provided is an electrode used in a battery, where the electrode has an electrode current collector and an electrode active material layer, the electrode active material layer contains an electrode active material of a single crystal system and an electrode active material of a polycrystal system as an electrode active material, the electrode active material of the single crystal system and the electrode active material of the polycrystal system are lithium transition metal composite oxide, the electrode active material layer has a first layer including a first surface on the opposite side of the electrode current collector and a second layer including a second surface on the electrode current collector side, the first layer contains the electrode active material of the single crystal system as a main component of the electrode active material, and the second layer contains the electrode active material of the polycrystal system as a main component of the electrode active material.SELECTED DRAWING: Figure 2

Claims

1. A battery having a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, The positive electrode includes a positive electrode current collector, a first layer positioned closer to the electrolyte layer than the positive electrode current collector, and a second layer positioned closer to the positive electrode current collector than the first layer. The first layer comprises a first positive electrode active material, The aforementioned second layer contains a second positive electrode active material, The first positive electrode active material has a primary particle diameter of 2.0 μm or more and 6.0 μm or less. The second positive electrode active material has a primary particle diameter of 0.5 μm or more and less than 1.0 μm. A battery in which, in X-ray diffraction using CuKα rays, the full width at half maximum of the peak of the first positive electrode active material at 2θ = 18.5° to 19.0° is smaller than the full width at half maximum of the peak of the second positive electrode active material at 2θ = 18.5° to 19.0°.

2. In all positive electrode active materials in the first layer, the proportion of the first positive electrode active material is the largest. The battery according to claim 1, wherein the proportion of the second positive electrode active material is the largest among all positive electrode active materials in the second layer.

3. The battery according to claim 1, wherein, in X-ray diffraction using CuKα rays, the full width at half maximum of the peak of the second positive electrode active material at 2θ = 18.5° to 19.0° is greater than 0.8°.

4. The battery according to claim 3, wherein, in X-ray diffraction using CuKα rays, the full width at half maximum of the peak of the first positive electrode active material at 2θ = 18.5° to 19.0° is 0.8° or less.

5. The first positive electrode active material has 20 or fewer primary particles bonded together. The battery according to claim 1, wherein the second positive electrode active material has more than 20 primary particles bonded to it.

6. The battery according to claim 1, wherein the first layer further comprises a fibrous carbon material.

7. The battery according to claim 6, wherein the fibrous carbon material is attached to the surface of the first positive electrode active material.

8. The battery according to claim 1, wherein the second layer further comprises particulate carbon material.

9. The battery according to claim 8, wherein the particulate carbon material is attached to the surface of the second positive electrode active material.

10. The battery according to claim 1, wherein the positive electrode further includes an intermediate layer between the first layer and the second layer, the intermediate layer containing at least one of the first positive electrode active material and the second positive electrode active material.

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